With a six-foot-five-inch liberal mayor and The Tonight Show being broadcast out of Studio 6B at 30 Rockefeller Plaza, New York will be experiencing something of a 1960s moment this spring. After two decades of conservative, developer-friendly leadership in City Hall, the incoming mayor, Bill de Blasio, will, for many New Yorkers, mark a welcome return to Lindsay-era progressive leadership. And with Jimmy Fallon moving The Tonight Show from Los Angeles back to New York, the program will be returning to its Carson-era roots—and, by extension, to the roots of late-night television. Steve Allen, the first host, headlined the show in New York from 1954 to 1957. He was a comedian best known for his funny phone calls as well as his quick comebacks: Do they get your program in…